Circuit breaker



July 18, 1961 l R. E. FRINK 2,993,105

CIRCUIT BREAKER Filed Deo. 13, 1957 5 Sheets-Sheet 1 g jij-MP7 -2-9 Q zo? `l 1 I /L 'L j ,33 3 2 5 |I| O j f 1 n, O 37 I :lg O 11, o ll 'A O 3L 'l r /HL [DI l l@ 53 6l y Tm l' 1| 1 63 5| Il |l 1| K 45 47 tu: u. si

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|55ki f |9| 55` E |93 IGI 2 5 WITNESSES INVENTOR W Russe|\E.Frink r BL- ATTORNEY July 18, 1961 R. E. FRINK 2,993,105

CIRCUIT BREAKER Filed Deo. l5, 1957 5 Sheets-Sheet 2 Fig. 2

July 18, 1961 R. E. FRINK CIRCUIT BREAKER Filed DSC. 13, 1957 3 Sheets-Sheet 3 United States Patent O 2,993,105 CIRCUIT BREAKER Russell E. Frink, Forest Hills, Pa., assgnor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Filed Dec. 13, 1957, Ser. No. 702,576 3 Claims. (Cl. 200--166) This invention relates to circuit breakers and more particularly to contact structures and mountings for air circuit breakers.

An object of the invention is to provide a circuit breaker embodying an improved contact structure that is compact and has a high momentary and continuous current-carrying capacity.

Another object of the invention is to provide a circuit breaker embodying an improved contact structure having high interrupting and current-carrying capacities.

Another object of the invention is to provide a circuit breaker embodying an improved contact structure having main, secondary and arcing contacts for heavy duty, which contact structure is so compact that all of the separating contacts may be located within an arc chute to prevent the arc from restriking outside of the arc chute where it will not be extinguished.

The invention has been illustrated by showing a contact structure and mounting arrangement therefor, designed for a magnetic air circuit breaker having a momentary current rating of 100,000 amperes, a continuous current-carrying rating of 3,000 amperes, and an interrupting rating of 50,000 amperes, but the invention may be used with advantage in circuit breakers of other ratings. Inv such heavy duty circuit breakers, it has been found that: (l) There should be main, secondary and arcing contacts in order to keep the main contacts in good condition to conduct the heavy currents, (2) The physical size of the contact assembly in the direction along the length of the moving contact arm should be as small as possible compared to the length of the moving contact arm to provide a maximum rate of contact separation, and to keep the separating main contacts from being significantly closer together at any point during their separation than are the separating arcing contacts, so that there will be little chance that the arc will restrike across the gap between the main contacts rather than to remain on the arcing contacts, and (3) The contact assembly should be so small that the main, secondary and arcing contacts may all be positioned up within the arc chute of the circuit breaker, so that if the arc should restrike between any of the contacts, due to the switching of capacitor banks or to abnormal circuit conditions, the restrikes will be confined to the arc chute where the arc will be extinguished by the arc-extinguishing structure provided. Accordingly, other objects of the invention are to provide for these features.

Another object of the invention is to mount the contact structure on insulated terminal studs having a compact and eicient arrangement for conducting the heavy currents to the contacts.

Other objects and advantages of the invention will be pointed out in the following description and illustrated in the accompanying drawings, which disclose, by way of example, the principle of the invention and the best mode, which has been contemplated, of applying that principle.

In said drawings:

FIG. 1 is a side elevational view, partly in section, of a circuit breaker embodying the principles of the invention.

FIG. 2 is an enlarged elevational view, partly in section, showing the improved contact structure in the closedcontact position;

Patented July 18, 1961 ice FIG. 3 is a horizontal sectional View taken through the contact structure on line III-III of FIG. 2;

FIG. 4 is a front elevational view of the stationary contact structure;

FIG. 5 is an elevational sectional view through the stationary contact structure taken on line V-V of FIG. 4;

FIG. 6 is a side elevational view showing one of the terminal studs having contact fingers thereon for plugging the breaker into a cubicle;

FIG. 7 is a vertical sectional view taken through one of the terminal studs; and

FIG. 8 is an elevational sectional view taken on line VIII-V111 of FIG. 1 and showing the terminal studs and the mounting means therefor.

The invention is illustrated as applied to a circuit breaker of the general type disclosed in Patent No. 2,717,292, issued September 6, 1955, to Russell E. Frink and Paul Olson and assigned to the assignee of the present invention.

The circuit breaker shown in the aforementioned patent is of the roll-out type and is mounted on a wheeled truck to facilitate movement of the breaker into and out of a cubicle in order to connect and disconnect the breaker in an electrical circuit.

Referring to FIG. 1 of the drawings, the circuit breaker Ais of the three pole type (only one pole being shown) and is mounted in a rigid frame comprising spaced triangular side plates 11 (only one being shown) rigidly secured together by cross members 13, 15, 17 and 19 to form a rigid frame. The frame, together with the circuit breaker, is mounted on wheels 20 to facilitate rolling the breaker into and out of a cubicle.

The circuit breaker comprises generally a set of separable contact means 21 for each pole, a common operating mechanism 23, a trip device 25 and closing means 27.

The contact structure comprises generally a stationary contact assembly `29 rigidly mounted on the inner end of an upper terminal stud 31 of hollow rectangular shape. The terminal stud 31 is encased in insulating material 33 and is rigidly clamped by means of bolts 35 between supporting aluminum cross bars 37 which extend across the three poles of the breaker and are secured by means of bolts 39 to the spaced side plates 11 of the frame. The contact structure also includes a movable switch arm 41 pivotally supported on a casting 43 rigidly secured to the inner end of a lower terminal stud 45 which also is of hollow rectangular shape. The lower terminal stud 45 (FIGS. 7 and 8) is surrounded by insulating material 47 and is rigidly clamped between supporting cross bars 49 by means of bolts 51. The cross bars 49 extend across all of the poles and are secured to the side plates 11 by means of bolts 53 (FIG. 8).

The terminal studs 31 and 45 are made hollow to provide `greater conductivity by reduction of the skin effect. A substantial reduction in the overall height of the breaker is effected by making the terminal studs rectangular rather than round, and supporting them between the cross bars 37 and 49 eliminates metal anges on the bushings.

The movable switch arm consists of two pairs of arms 55 and 57 (FIG. 3) bolted together at their upper ends by means of bolts 58 (FIG. 2) with a movable contact member 59 between them. The lower ends of the pairs of switch arms 55 and 57 are spaced apart -as shown in FIG. 3 and each pair is pivotally supported by means of pins 61 (only one being shown) supported in projection 63 (FIGS. 1 and 2) on the casting 43. Spring washers 65 disposed on the outer sides of each pair of switch arms 55 and 57 provide good contact pressure between the switch arms and the projections 63. The movable switch member 59 has an arcing contact 67 (FIG. 2) rigidly secured to the upper end thereof and a secondary contact 69 rigidly secured thereto adjacent the lower end thereof. Arc resisting main movable contact strips 71 are rigidly secured to the opposite edges of the contact member 59 for engagement with main stationary contact fingers 73.

The stationary contact assembly 29 is mounted on a conducting block 75 rigidly secured to the inner end of the upper terminal stud 31 and comprises a plurality of stationary contact lingers 73 and a plurality of stationary contact lingers 77 which at their upper ends Ihave stationary arcing contacts 79 rigidly mounted thereon for cooperating with the movable arcing contact 67. Stationary secondary contacts 81 are mounted on the lower ends of the lingers 77. Each of the main stationary contact `lingers 73 has an a-rc resisting contact 83 rigidly secured thereto for cooperating with the movable main contact strips 71. The main stationary contac-t ngers 73 are biased inwardly to provide pressure by springs 85 surrounding rods 87 which extend horizontally through openings in the contact lingers 73 and through an opening in a contact support member 89 rigidly secured to the block 75. The springs 85 are compressed between the contact lingers 73 and washers 91 which are retained in place by nuts 93 threaded onto the outer ends of the rods 87. The springs 85 press rounded inner ends of the main contact lingers against the contact support member 89 to provide good electrical contact. Each of the contact lingers 73 is provided with an inwardly projecting portion 95 which extends into recesses 97 in the contact support members 89 to preve-nt longitudinal movement of the lingers.

' The main contact lingers 73 are positioned in two vertical opposed rows, with half of the lingers in each row. "I 'he length of the rows runs, in the same genera-l direction as the length of the moving switch arm and in the same direction as the height, rather than the width of the arc chute. This keeps the lwidth of the s-tationary contact assembly to a minimum and makes it possible to position the main contacts within the arc chute, in spite of the large number of main contact members required for the heavy currents. In the specific embodiment shown for the purposes of illustration, there are ten main contact members 73, and if these ten main contacts had been put in a single horizontal row, generally perpendicular to the length of the moving switch arm, the width of the assembly would be -too great to be positioned in the portion of the arc chute which is lined with arc-resisting material and which is effective to act upon the arc to extinguish it.

The contact lingers 77 are pivotally and slidably supported at their lower ends by a rod 103 having its end supported in slots 1115 (FlG. 2) in forwardly extending projections 167 of a cage 99. The contact fingers 77 are provided with openings 109 which are larger than the diameter of the rod 193 to provide for individual movement of the contac-t lingers. Flexible conductors I111 secured by means of bolts 113 to the Contact lingers 77 and by bolts 115 to the contact support member 89 elec,- trically connect the lingers 77 through the member 89 and the block 75 to the terminal stud 31.

The upper ends of the contact lingers 77 are controlled in their movement by a rod 117 (FIGS. 2, 4 and 5) extending through ropenings 119 in the fingers. The openings 11'9 are somewhat larger than the diameter of the rod 117 to provide for individual movement of the lingers 77. The ends of the rod 117 engage in enlarged slots 12H1 (FIG. 2) in projections 123 of the retaining cage 99 and the rod 117 is retained in position by small retaining plates 125 secured to opposite sides of the projection I123 by means of bolts 127 and engaging the ends of the rod 117.

The lower ends of the contact lingers 77 are individually biased for secondary contact pressure by means of springs 129 compressed between spring seats in the retaining cage 99 and spring guides 131 on the contact lingers. The upper ends of the contact lingers 77 are biased by a pair of springs 133 (FIG. 5) compressed be.,

tween a spring seat on a portion 135 of the retaining cage 99 and a movable spring seat 137. A pressure equalizing member 139 in the shape of an equilateral triangle is provided with `a projection 141 on each of its apices which engage in notches 143 in the contact lingers 77. The equalizer 139 is also provided with a socket (not shown) at its geometric center which is engaged by a projection (also not shown) on the movable spring seat 137. The upper projection 1.41 on the pressure equalizer 139 engages a notch 143 in the center one of the con4 tact lingers 77 and the lower projections engage the notches 143 yfor the outer lingers 77 thus equalizing the pressure of the springs 133 on all three of the fingers 77.

The use of the spring-biased main, secondary and arcing contacts, as at 73, 81 and 79, all on the stationary Contact assembly, has the advantage that the moving con tact assembly is greatly simplified in that one rigid structure includes the mo-ving main, secondary and arcing contacts, which may all be brazed to a common contact member. Thus, the main contact surfaces 71, the secondary contact surfaces 69 and arcing contact surfaces 67 are rigid with each other and with the moving switch arm 57, and there is no need on the moving contact assembly for any biasing springs, any sliding contact surfaces, or any flexible current conductors.

Each of the terminal studs 31 and 45 are provided With a plurality of pair-s of spring biased contact lingers 145 as shown in FIG. 6, for engaging lixed contacts 147 having flat side surfaces to connect the breaker in an electrical circuit.

The use of the rectangular terminal studs 31 and 45 has the advantage that each of the two opposed parallel sides of the rectangle may directly support a plurality of pairs of the opposed Contact lingers in a straight row without the use of any intermediate member in the current path. This is true of both of the terminal studs 31 and 45. This keeps the number of joints in the current path to a minimum and facilitates the carrying of heavy currents. The outer contact finger 145 of each pair in the row directly engages at its inner end with the outer surface of one side of the hollow rectangle and the inner linger of each pair in each row similarly engages the inner surface of one side of the hollow rectangle.

The movable switch arm 41 (FIG. 1) for operating the movable contacts (there being a switch arm 41 for each pole of the breaker) is operatively connected by means of an insulating operating rod 149 to the operating mechanism 23. The upper ends of the operating rods 149 are pivotally connected by means of pivot pins 151 to the corresponding switch arms 41, and the lower ends of the operating rods are connected by suitable means to an angular crossbar 153 which is common to all of the poles of the breaker.

The specific structure of the operating mechanism, trip mechanism and the closing means shown are fully disclosed in Patent No. 2,515,994, issued July 18, 1950, to Joseph D. Findley, Alvin W. Ogg and Fritz E. Florschutz and assigned to the assignee of the present invention, for which reason only a brief description of these mechanisms is given herein.

The crossbar 153 is pivotally connected at its ends by pivot pins 155 (only one being shown) to an operating lever 161 which is pivotally mounted on a shaft 167 supported in the side members of a generally U-shaped frame 169. The frame 169 is supported on the cross members 13, 17 and 19 and is shown partly broken away more clearly to show the operating mechanism.

In addition to the operating lever 161, the operating mechanism consists of a closing lever 171 also pivotally mounted on the shaft 167 and connected by means of a link 173 to the moving armature 175 of the closing solenoid 27. The operating lever 161 and the closing lever 171 are connected by means of an underset thrust-transmitting toggle comprising toggle links 177 and 179 which are pivotally connected together by a knee pivot pin 181.

The toggle link 177 is pivotally connected to the operating lever v161 and the toggle link `174 is pivotally connected to the closing lever 1'77 The closing lever 171 is held in the closed position by a spring biased latch 183 which normally engages a roller 185 on the closing lever 171 and holds the latter in the position shown.

The toggle 177 and 179 is releasably held in a slightly underset position by a latch member 187 mounted on the shaft 167 for rotary movement relative thereto. A link 189 connects the latch member 187 to the knee of the toggle 177-179 and the latch member is normally releasably held in latching position by the latching and tripping mechanisms 25 thus holding the toggle 177- 179 in thrust-transmitting position. The latch member 187 is held in latching position by an intermediate slip-off latch 191 which, in turn, is held in latching position by a trigger latch 193. A tripping electromagnet 195 is provided to operate the latch mechanism and elect release of the operating mechanism and opening of the breaker.

When an overload current occurs, the tripping electromagnet 195 is energized and operates the latch mechanism to eect release of the latch member 187. Upon release of the latch member 187, the toggle 177--179 c01- lapses permitting clockwise rotation of the operating lever 161 and opening movement of the switch arms 41 for the several poles of the breaker.

During the opening operation, the toggle 177--179 automatically is reset to thrust-transmitting position and the latch member 187 is reset and relatched. This is effected by spring means 197 which is connected under tension between the armature 175 of the closing solenoid 27 and the closing lever 171 at a point near the shaft 167. When the toggle 177- 179 collapses during an opening operation, a roller 199 on the toggle link 179 engages a nose 201 on the latch 183 and moves the latch to disengage it from the roller 185. This releases the closing lever 171 whereupon the spring 197 moves the armature 175 and, through the link 173 connecting the armature to the closing lever 171, moves the latter clockwise. This movement extends the toggle 177-179 to its thrust transmitting position and, through the link 189, rotates the latch member 187 clockwise to its latching position, permitting resetting of the latch mechanism. Thereafter, the circuit lbreaker is closed by energization of the closing solenoid 27 from any suitable source. When energized, the solenoid attracts its armature 175 and, through the link 173, rotates the closing lever 171 counterclockwise. Since, at this time, the toggle 177-179 is held in thrust transmitting position, the movement of the closing lever is transmitted therethrough and actuates the operating lever 161 and the rods 149 to close the contact means for the several poles of the breaker. As the mechanism reaches the closed position, the latch 183 re-engages the roller 185 and restrains the breaker mechanism in the closed contact position.

The separating contacts are all disposed well within an arc-extinguishing structure indicated generally at 205 (FIGS. 1 and 2) so that when the contacts separate and the moving contact means moves to the full open position, the arc drawn between the separating arcing contacts is drawn into the arc-extinguishing structure where it is quickly extinguished. The arc extinguisher 205 may be of the general type shown in Dickinson and Frink Patent No. 2,442,199, issued May 25, 1948, or in Frink Patent No. 2,769,065, issued October 30, 1956. As seen in FIG. l, the arc-extinguisher 205 is pivotally mounted by means of spaced brackets 207 (only one being shown) secured to the upper crossbar 37 by the bolts 35 which clamp the upper terminal stud in position.

The invention provides an improved contact structure which increases the momentary and continuous currentcarrying capacity in a small, compact contact arrangement which permits placing the entire separating contact structure inside the arc chute, hence, any restrking of the arc will occur between the contact structure and will be confined within the arc-extinguisher.

Certain features disclosed in this application are disclosed and claimed in a continuation of this application Serial No. 57,320, iiled September 20, 1960, and assigned to the assignee of the instant application.

While the invention has been disclosed in accordance with the provisions of patent statutes, it is to be understood that various changes in the structural details and arrangement of parts may be made without departing from the spirit of the invention.

I claim as my invention:

1. In a circuit breaker, a frame comprising spaced side members, a pair of terminal members of hollow rectangular cross section, spaced cross bars mounted on and extending between said spaced side members, means rigidly clamping said terminal members between said crossbars, movable contact means pivotally mounted on the inner end of one of said terminal members, a stationary contact structure mounted on the inner end of the other of said terminal members, said stationary contact structure comprising a contact support member, a plurality of pairs of main stationary contact members disposed on opposite sides of said support member, a plurality of intermediate stationary contact members disposed between said pairs of main stationary contact members, and said movable contact means cooperating with said stationary contact structure to open and close said circuit.

2. In a circuit breaker, a frame, a terminal member of hollow rectangular cross section, insulating material around the terminal member and having at opposed outer surfaces, a pair of spaced cross bars clamped against the said at opposed outer surfaces of the insulating material and securing the hollow rectangular terminal member to the frame, a contact structure supported on the inner end of the terminal member, and two rows of opposed pairs of Contact ngers supported on the outer end of the terminal member.

3. In a circuit breaker, a frame, one or more pairs of terminal members of hollow rectangular cross section, insulating material around each terminal member and having at opposed outer surfaces, spaced cross bars clamped against the said flat opposed outer surfaces of the insulating material and securing the hollow rectangular terminal members to the frame, movable and stationary contact structures supported on the inner ends of said terminal members of hollow rectangular cross section, two rows of opposed pairs of contact ngers supported on the outer end of each of said terminal members, each pair of contact ngers in one row having a iinger engaging the outer surface of one side of the associated hollow rectangle and another finger engaging the inner surface of the same side of the associated hollow rectangle, and each pair of contact fingers in the other row having a finger engaging the outer surface of another side of the associated hollow rectangle and another finger engaging the inner surface of the same other side of the associated hollow rectangle.

References Cited in the le of this patent UNTTED STATES PATENTS 1,843,804 Christie Feb. 2, 1932 1,978,246 Bauerschmidt Oct. 23, 1934 2,324,891 Thumim July 20, 1943 2,426,387 Caswell Aug. 26, 1947 2,644,875 Miller July 7, 1953 2,646,482 Wood et al. July 2l, 1953 2,708,699 Jansson May 17, 1955 2,717,292 Frink et al. Sept. 6, 1955 2,761,040 Ulrich Aug. 28, 1956 2,849,579 Frink Aug. 26, 1958 FOREIGN PATENTS 535,461 Great Britain Apr. 9, 1941 

